1. Field of the Invention
The present invention relates to novel anti-ganglioside glycolipid monoclonal antibodies and more specifically to monoclonal antibodies capable of recognizing gangliosides GQ.sub.1b and GT.sub.1a and a novel hybridoma which produces such monoclonal antibodies as well as a method for generating the hybridoma.
2. Description of the Prior Art
In 1975, Kohlor et al. developed a hybridoma which produces an anti-sheep red blood cell antibody and which is generated by fusing spleen cells derived from an immunized animal and mouse myeloma cells. A clone which is a hybridoma originated from a single cell can be isolated from such hybridoma cells (so-called "cloning") because of its high proliferation potency. All the antibodies produced by such a cloned hybridoma are identical with each other and their antigen-recognizing sites are also identical. Therefore, they have identical specificity to a specific antigen. In addition, the stable supply of such a monoclonal antibody can be ensured since the hybridoma cells can be stored in the frozen state, for instance, in liquid nitrogen.
Conventional anti-sera have been prepared by letting the serum from an immunized animal absorb a variety of antigens. Therefore, they contain a large number of antibody molecules originated from different B cells (polyclonal) and hence often cause cross reactions with other antibodies. Thus, it is difficult to obtain anti-sera exhibiting excellent specificity according to such methods. However, the foregoing cell fusion technique permits the production of monoclonal antibodies which can specifically react with a specific antigen.
Antibodies are proteins which can recognize a molecule known as the "antigen" inherent thereto and can be bound to the same. The monoclonal antibody is an antibody having a single antigen-recognizing site and hence recognizes only one kind of antigenic determinant. Various techniques for producing monoclonal antibodies and those for generating hybridomas capable of producing the same are detailed in "Monoclonal Hybridoma Antibodies: Techniques and Applications", edited by John G. Hurrell, 1983.
The glycolipids of mammalian cells belong to the category of so-called sphingoglycolipids and comprise (i) a lipid structure referred to as ceramide composed of a long-chain aminoalcohol called sphingosine to which a fatty acid is acid amido-bound and (ii) various combination of sugars selected from the group consisting of glucose, galactose, N-acetylglucosamine, N-acetylgalactosamine, fucose and sialic acid which are bonded to the structure through glycoside bonds. Among these, the glycolipids carrying sialic acid are, in particular, referred to as "gangliosides".
These compounds are generally located in the outer molecular layer of the two-molecular-layer structure of lipids of cell membrane and it has been thought, from recent investigations, that the compounds play an important role in the functions such as a reception of information for discrimination in the cells and response to such information; receptor functions; differentiation; and proliferation, malignant change, behaviors or the like of cells.
Among these gangliosides, ganglioside GQ.sub.1b can be considered to be a marker of a certain kind for the growth, differentiation or the like of nerve cells.
Therefore, the development of monoclonal antibodies specific to gangliosides GQ.sub.1b and GT.sub.1a have been an important subject for the elucidation of sugar chain's roles in cell functions and for studying the development of animals, since the monoclonal antibody has high specificity to a specific antigen and thus can detect the same in high sensitivity.